1. Field of the Invention
The present invention relates to improving the performance and efficiency of an axial fan.
2. Background of the Related Art
Computer systems include numerous components that use electrical energy and produce heat as a byproduct. Typically, these components are organized in a chassis for efficient placement, storage and operation. The heat produced by the components within a chassis may be removed by forcing cool air into the chassis, across the components and then out of the chassis. This forced air circulation may be done with one or more air moving device positioned within the chassis or external to the chassis.
An axial fan is a common type of air moving device that is used in many applications, including forced air cooling in a computer chassis. An axial fan, or axial-flow fan, has blades that force air to move parallel to a central shaft about which the blades rotate. Depending upon the chassis dimensions and the air flow requirements of the components within the chassis, a fan assembly may include multiple fans.
An axial fan may operate at various speeds as determined by a fan controller, for example to maintain component temperatures below a setpoint temperature. Because component cooling requirements may change over time with varying workload, a fan controller may frequently adjust the fan speed. While it is important to keep component temperatures from reaching levels that can damage the components, it is also important to conserve electrical power to the fans and avoid using unnecessarily high fan speeds.
The design of the fan may play a significant role in the operating efficiency of the fan. For example, a first fan may be optimized for performance so that it can operate over a wide range of air flow rates, while a second fan may be optimized for electrical efficiency over a much narrower range of air flow rates. The best choice of a fan for a given system chassis may change over time in response to the current operating conditions of the components within the chassis.